Sure some games have been released to the public.
There are a lot of the original creators of the games that have died already, a lot of publishers that went out of business and only exist on paper on some underwriter's desk.
I used to work on side-projects in the 1980's and 1990's, somehow they ended up on the Internet for free. Nobody is interested in me making modern day versions of them. I tried Kickstarter and Indiegogo but nothing.
Heck I an others even tried to document the classic BBS DOS based games on Wikipedia, who deleted them because the only source for them were Boardwatch Magazine that is rare and out of print.
I've seen Classic Remakes like Bard's Tale that was basically a pale imitation of the original game with better graphics but not very good game play. True it did include the original game in an emulator, but it failed. Another remake was called Devil's Whiskey to avoid copyright in names, but it had the classic Bard's Tale elements to it. For some reason Devil's Whiskey failed as well.
You do see people remaking classic games on iPhone and Android devices. Then using a different name.
In the Atari 2600 world Activision and iMagic made games based on other games but with different graphics and sounds and different names. Activision had Chopper Command that was like the William's Defender arcade game. Activision also had Chicken that was sort of a Frogger clone. iMagic had Demon Attack that was sort of a Galaga clone with a twist. I think Atlantis by iMagic was supposed to be a Missile Command sort of game as well.
You can see all of the 3D shooters based on Doom and Quake on Steam, in fact you can buy Doom and Quake on Steam and it runs them in DOSBOX.
Sure I spent a whole lot of money on DOS and Windows video games. I still have the original disks somewhere in boxes in my basement. I still have a Packard Bell 486 clone that can play them too.